RAD9, RAD1, HUS1-interacting nuclear orphan protein
RHINO, or RAD9, RAD1, HUS1-interacting nuclear orphan, is a family of eukaryotic proteins. Under genotoxic stresses such as ionizing radiation during the S phase, RHINO plays a role in DNA damage response signalling. It is recruited to sites of DNA damage through interaction with the 9-1-1 cell-cycle checkpoint response complex and TOPBP1 in a ATR-dependent (ataxia telangiectasia and Rad3-related) manner. It is required for the progression of the G1 to S phase transition of breast cancer cells, and it is known to play a role in the stimulation of CHEK1 phosphorylation. It interacts with RAD9A, RAD18, TOPBP1 and UBE2N.